Add failed_once category to Sheriff-O-Matic.

Tools/GardeningServer/model/test/ct-failure-group-tests.html

Index: Tools/GardeningServer/model/test/ct-failure-group-tests.html
diff --git a/Tools/GardeningServer/model/test/ct-failure-group-tests.html b/Tools/GardeningServer/model/test/ct-failure-group-tests.html
index f94c7eb41f117022db8aaa3186431364bb864f4e..83ca07fb8b257f5ab05a2d311b60645d29483d6c 100644
--- a/Tools/GardeningServer/model/test/ct-failure-group-tests.html
+++ b/Tools/GardeningServer/model/test/ct-failure-group-tests.html
@@ -34,6 +34,21 @@ describe('ct-failure-group', function() {
       var group = new CTFailureGroup([newFailureWithAnnotation({snoozeTime: Date.now() + 1000 * 1000})], undefined);
       assert.equal(group.category, 'snoozed');
     });
+
+    it('should be "failed_once" when there is only one failure', function() {
+      var failure = newFailureWithAnnotation();
+      failure.resultNodesByBuilder = {some_key: {failingBuildCount: 1}}
+      var group = new CTFailureGroup([failure], undefined);
+      assert.equal(group.category, 'failed_once');
+    });
+
+    it('should not be "failed_once" when there is more than one failure', function() {
+      var failure = newFailureWithAnnotation();
+      failure.resultNodesByBuilder = {some_key: {failingBuildCount: 1},
+                                      other_key: {failingBuildCount: 1}}
+      var group = new CTFailureGroup([failure], undefined);
+      assert.equal(group.category, 'default');
+    });
   });
 
   describe('snooze', function() {